| Title | Seismic Monitoring of the Rittershoffen EGS Project (Alsace, France) |
|---|---|
| Authors | Vincent MAURER, Nicolas CUENOT, Emmanuel GAUCHER, Marc GRUNBERG, Jérôme VERGNE, Hervé WODLING, Maximilien LEHUJEUR, Jean SCHMITTBUHL |
| Year | 2015 |
| Conference | World Geothermal Congress |
| Keywords | Geothermal Project, Rittershoffen, Induced Microseismicity, Monitoring, Seismic Network. |
| Abstract | The ECOGI joint venture (Electricité de Strasbourg group, Roquette Frères and Caisse des Dépôts et de Consignation) is in charge of the development and the exploitation of the Rittershoffen Enhance Geothermal System (EGS) located 6 km east of Soultz-sous-Forêts, in Northern Alsace, France. This EGS reservoir is one of the very few currently under development in Europe and is designed to produce 24 MWth (170 °C, 70 L/s). The first well of the doublet (GRT1) was completed end of 2012 and reaches, at 2580 m depth, the crystalline fractured basement which constitutes the reservoir formation together with the overlaying Buntsandstein sandstones. A reservoir development strategy was defined, and first consisted in enhancing the connections between GRT1 and the fractured reservoir. These operations were applied in two sequences, respectively in April 2013 and in June 2013. The stimulation operations were successful, providing the expected enhancement of the hydraulic properties of the well. The drilling of the second well, GRT2, started in March 2014. Since 2012, the induced microseismicity of both Rittershoffen and Soultz-sous-Forêts geothermal projects has been monitored by a seismic network composed of 12 permanent surface stations. To increase the network detection capability, the ECOGI management decided to deploy a temporary network composed of 16 additional real-time telemetered surface stations, in collaboration with the KIT (Karlsruhe University, Germany). Waveforms from all stations are currently acquired in real-time via queries supported by a SeisComp3 server. Microseismicity was carefully monitored during the operations carried out to enhance the reservoir production. The main objective was to avoid inducing a microseismic event felt by population. On the top of that, several innovative other research projects motivated the installation of non-telemetered stations, increasing the network to 300 stations within an area of about 15 km around the drilling platform, thereby constituting an unprecedented and unique seismological dataset associated to a geothermal EGS project. |